Outdoor enclosures for electronic systems and telecommunications systems are known. Some enclosures also include batteries, such as valve-regulated lead acid (VRLA) batteries as a backup power supply for the electronics. It is important to regulate the temperature of the inside of the enclosure to specified levels. This is necessary in order to ensure the proper operation of the electronics and also the batteries.
If the equipment within the enclosure produces a large amount of heat, the only method of cooling that is adequate for the task is direct air cooling. For other equipment which is less demanding, a heat exchanger may be sufficient. Active electronic or telecommunications equipment will operate properly at temperatures up to 50, 55 or even 65° C. However, if batteries are present within the same enclosure, the batteries rapidly lose the ability to retain a charge if the temperatures exceed 30° C. for an extended period of time. Thus, some form of air-conditioning is necessary to maintain the temperatures of the batteries near 25° C.
Many outdoor enclosures must use air conditioning to keep the batteries at a proper temperature. However, in such outdoor enclosures, the air conditioner also acts to cool the electronics. The electronics are cooled to a greater degree than is required by the electronics itself. The over cooling of the electronics can lead to flash condensation on the electronics when the door is opened and humid ambient air enters the enclosure. Thus, the use of air-conditioning may properly cool the batteries, but overcool the electronics. On the other hand, direct air cooling or a heat exchanger may allow the battery temperature to be too high, especially in the higher ambient temperature areas, or may allow the battery temperature to be too low in lower ambient temperature areas. Thus, none of these arrangements can provide for optimal temperature control suitable to both the batteries and electronics.